The long range goal of this project is to understand how the mechanism of voice production is changed by phonosurgery. This goal will be reached by longitudinal assessment of patients with glottic insufficiency treated by augmentation of autogenous collagen or fat, by arytenoid adductions, by thyroplasties, and by grafts. The same procedures will be performed on excised human larynges for in vitro studies and histologic examination. Glottic insufficiency is a significant health problem commonly resulting from laryngeal nerve injury, conservation extirpative laryngeal surgery, laryngeal trauma, neurologic disease, and aging. The insufficiency can range from mild gapping accompanied by vocal fatigue to a large glottic aperture with no closure and complete aphonia. The result is socially and occupationally disabling and compromises the quality of life. There are surgical techniques available to correct these problems, but the impact of the procedures on the biomechanics of vibration is not well understood, patient selection criteria has not been defined, and many patients have persistent voice problems. There are four major areas of study: (1) METHODOLOGICAL: to modify phonosurgical techniques and specify patient selection criteria for optimal correction of glottic insufficiency, and to standardize assessment for maximum specificity and sensitivity of glottic impairment; (2) DESCRIPTIVE: to show how tissue morphology relates to each surgical procedure's outcome using magnetic resonance imaging and 3-D reconstructions, videostroboscopy, aerodynamic, and acoustic analysis on dysphonic clinical populations; (3) EMPIRICAL: to study vocal fold vibration on excised human larynges and thereby determine the specific impact of placement and volume of injected material and thyroplasty shims on the voice signal; (4) LONGITUDINAL: to determine the clinical outcome of four different evolving procedures in patients presenting with symptomatic glottic insufficiency.